SAN DIEGO, Calif. and Deerfield, Ill., December 21, 2011 — Zogenix, Inc. (NASDAQ: ZGNX), a pharmaceutical company commercializing and developing products for the treatment of central nervous system disorders and pain, and Astellas Pharma US, Inc. (Astellas),a U.S. subsidiary of Tokyo-based Astellas Pharma Inc.(Tokyo:4503) announced today that the co-promotion of SUMAVEL DosePro (sumatriptan injection) Needle-free Delivery System will end on March 31, 2012. SUMAVEL DosePro is Zogenix's first commercial product and was launched with Astellas in January 2010 for the acute treatment of migraine and cluster headache.

Beginning in the second quarter of 2012, Zogenix will assume full responsibility for the continued commercialization of the brand, with a focus on headache specialists, neurologists and primary care physicians who treat a significant number of migraine patients. The companies plan to agree on a detailed customer transition plan by February 1, 2012, with a goal of uninterrupted access and service to physicians within the Astellas segment.

Under the amended co-promotion agreement, neither company will incur any penalty payments related to the early termination of the agreement which was originally slated to expire June 30, 2013. Astellas will contribute its agreed portion of marketing expenses through March 31, 2012, and will continue to earn a service fee based on product sales to its physician segment during that period. Zogenix will no longer pay service fees to Astellas for sales of SUMAVEL DosePro beginning with the second quarter of 2012. Zogenix will be issuing a separate announcement commenting on the strategic direction for SUMAVEL DosePro in 2012.

About SUMAVEL DosePro

SUMAVEL DosePro (sumatriptan injection) is indicated for the acute treatment of migraine attacks, with or without aura, and the acute treatment of cluster headache episodes.

SUMAVEL DosePro should only be used where a clear diagnosis of migraine or cluster headache has been established. SUMAVEL DosePro is not intended for the prophylactic therapy of migraine or for use in the management of hemiplegic or basilar migraine and should not be administered intravenously. For a given attack, if a patient does not respond to the first dose of SUMAVEL DosePro, the diagnosis of migraine or cluster headache should be reconsidered before administration of a second dose.

Important Safety Information

SUMAVEL DosePro is contraindicated in patients with uncontrolled hypertension, in patients with history, symptoms or signs of ischemic heart disease, coronary artery vasospasm, cerebrovascular or peripheral vascular disease including ischemic bowel disease and in patients with other significant underlying cardiovascular diseases or known hypersensitivity to sumatriptan. SUMAVEL DosePro should not be given to patients in whom unrecognized coronary artery disease is predicted by the presence of risk factors without a prior cardiovascular evaluation.

Serious cardiovascular events, including death, have been reported when taking sumatriptan, including patients with no findings of cardiovascular disease. Considering the extent of use of sumatriptan in patients with migraine, the incidence of these events is extremely low. Cerebrovascular events, some fatal, have been reported in patients treated with sumatriptan. In a number of cases, it appears possible that the cerebrovascular events were primary, sumatriptan having been administered in the incorrect belief the symptoms experienced were a consequence of migraine when they were not. It is important to advise patients not to administer SUMAVEL DosePro if a headache being experienced is atypical.

Do not use SUMAVEL DosePro and any ergotamine-containing or ergot-type medication within 24 hours of each other; do not use SUMAVEL DosePro and another 5-HT1 agonist (e.g. triptan) within 24 hours of each other (with the exception of a single dose of another sumatriptan product, provided the doses are separated by at least 1 hour). SUMAVEL DosePro is not generally recommended for use with MAO-A inhibitors. The development of a potentially life-threatening serotonin syndrome may occur with triptans, including treatment with SUMAVEL DosePro, particularly during combined use with selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs). SUMAVEL DosePro should be used during pregnancy only if the potential benefit justifies the potential risk.

In controlled clinical trials with sumatriptan injection, the most common adverse reactions were injection site reactions, tingling, warm/hot sensation, burning sensation, feeling of heaviness, pressure sensation, feeling of tightness, numbness, feeling strange, tight feeling in head, flushing, tightness in chest, discomfort in nasal cavity/sinuses, jaw discomfort, dizziness/vertigo, drowsiness/sedation and headache.

For full prescribing information, please click here: http://www.zogenix.com/downloads/SV0468.0611_SDP_PI.pdf

For more information about SUMAVEL DosePro, please visit www.SUMAVELDosePro.com.

About Zogenix

Zogenix, Inc. (Nasdaq:ZGNX), with offices in San Diego and Emeryville, California, is a pharmaceutical company commercializing and developing products for the treatment of central nervous system disorders and pain. Zogenix's first commercial product, SUMAVEL® DosePro® (sumatriptan injection) Needle-free Delivery System, was launched in January 2010 for the acute treatment of migraine and cluster headache. Zogenix's lead product candidate, Zohydro™ (hydrocodone bitartrate), is a novel, oral, single-entity (without acetaminophen) extended-release capsule formulation currently in Phase 3 clinical trials for the treatment of moderate to severe chronic pain in patients requiring around-the-clock opioid therapy. Zogenix's second DosePro product candidate, Relday™, is a proprietary, long-acting injectable formulation of risperidone for the treatment of schizophrenia.

About Astellas

Astellas Pharma US Inc., located in Deerfield, Illinois, is a U.S. affiliate of Tokyo-based Astellas Pharma Inc. Astellas is a pharmaceutical company dedicated to improving the health of people around the world through the provision of innovative and reliable pharmaceutical products. The organization is committed to becoming a global category leader in focused areas by combining outstanding R&D and marketing capabilities. For more information about Astellas Pharma US Inc., please visit our website at www.us.astellas.com.

Forward Looking Statements

Zogenix cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. Words such as "believes," "anticipates," "plans," "expects," "indicates," "will," "intends," "potential," "suggests," "assuming," "designed" and similar expressions are intended to identify forward-looking statements. These statements are based on the company's current beliefs and expectations. These forward-looking statements include statements regarding the attributes of SUMAVEL DosePro and its usefulness as a therapeutic option in relieving migraine pain and symptoms.The inclusion of forward-looking statements should not be regarded as a representation by Zogenix that any of its plans will be achieved. Actual results may differ from those set forth in this release due to the risk and uncertainties inherent in Zogenix's business, including, without limitation: the market potential for migraine treatments, and Zogenix’s ability to compete within that market; inadequate therapeutic efficacy or unexpected adverse side effects relating to SUMAVEL DosePro that could delay or prevent commercialization, or that could result in recalls or product liability claims; Zogenix's ability to secure another co-promotion partner to promote SUMAVEL DosePro on acceptable terms, or at all; and other risks described in the company's prior press releases and filings with the Securities and Exchange Commission.

You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Zogenix undertakes no obligation to revise or update this release to reflect events or circumstances after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995.

SUMAVEL®, DosePro®, ReldayTM and ZohydroTM are trademarks of Zogenix, Inc.